Preparation of diesters of aliphatic oxophosphonic acids



Patented Sept. 30, 1952 PREPARATION OF DIESTERS OF ALIPHATIC OXOPHOSPHONIC ACIDS Earl W. Gluesenkamp, Centerville, and Tracy M.

Patrick, Jr., Dayton, Ohio, assignorsto Monsanto Chemical Compan poration of Delaware y, St. Louis .Mo., a cor.-

No Drawing. Application August 25, 1950,

Serial No. 181,574

17 Claims. 1

phorus compounds, provides an improved procass of preparing aliphatic oxo-phosphonates, and also provides some new and highly useful compounds which are prepared by said process.

We have found that diesters of aliphatic oxophosphonic acids may be readily prepared by contacting a diester of phosphorous acid with an rip-unsaturated aliphatic ketone in the presence of a free-radical liberating agent. The reaction isone of simple addition in which a mole of the di-ester adds to at least-one afi-Olfifilli'C double bond of the ketone. It appears to be general for all diesters of phosphorous acid and for all aliphatic rip-unsaturated ketones, but it is of special importance in connection with the preparation of hydrocarbon di-esters of aliphatic, saturated or mono-olefinic oxo-phosphonic acids, the reaction in this case proceeding substantially according to the scheme I iii? it i YO.P.OY R.C:O.C.X R.C.CH.CX

, ll Free Radical V ,0 Yo.iI .0Y I

in which Y is a hydrocarbon residue, R is selected from the class consisting of hydrogen and alkyl radicals and X is selected from the class consisting of alkyl and alkenylradicals. The preferred phosphites, i. e., phosphites with which the addition reaction proceeds easily and smoothly without substantial formation of by-products are those in which Y is selected from the class consisting of alkyl, cycloalkyl, aryl, alkaryland aralkyl radicals of from 1 to 12 carbon atoms. The preferred ketones are those in which R is selected from the class consisting of hydrogen and alkyl radicals of from 1 to 8 carbon atoms and X is selected from the class consisting of alkyl radicals of from 1 to 8 carbon atoms and alkenyl radicals of from 4 to 8 carbon atoms.

One class of ketones which may be employed in the present process-comprises alkyl alkenyl'ketones, the reaction with such ketones proceeding substantially as follows: Y

in which Y is selected from the class consisting of alkyl, cycloalkyl, aryl, aralkyl and alkaryl radicals of from 1 to 12 carbon atoms; R is selected from the class consisting of hydrogen and alkyl radicals of from 1 to 8 carbon atoms and alk denotes anwalkyl'radical of from -1 130,8 carbon atoms. As illustrative of ketones having the above structure and useful for the present purpose may be mentioned the alkyl vinyl ketones including methyl, ethyl, propyl or isobutyl vinyl ketone, mesityl oxide and other higher alkyl ketones having an olefinic double bond conjugated with the carbonyl group, e. g., ethy1ideneacetone, CHsCI-I CH.CO.CH3, isobutylideneacetone (CH3) I2CH.CI-I2 CH..CO-.CH3

isoamylideneacetone I I I I (QHa) 2CH.CH2CH CH.CO.C'H3 3-methyl-3-hepten-5-one CH3.CH2.C (CH3) ZCH.CO.CH2CH3 8-decen-2-one CH3(CH2)5.CH}CH .CO.CH3, 2,3,6- trimethyl-3-hepten-5-one (CH3) 2CH.C(CH3) :CI-I.CO.CH(CH3) 2 and B-methyl-fi-tridecen-B-one CH3 (CH2) 4C(CH3) 2CH.CO'. (CI-I2) 4C Addition of the phosphite'occurs at the double bond, the product obtained with mesityl oxide and diethylphosphite, for example, being diethyl 2 -methyl 4-oxo-pentane-2-phosphonate CH3 i) I I v CH3.(J.CH.-C.CH;

Another class of ketones which may be employed in thepresent process comprises dialkenyl ketonesithe reaction withsuch ketones proceeding substantially according to the scheme:

. YO.H.OY

in which Y. and Rare defined above and 'alkenyl denotes an alkenyl radical of from 2 to 8 carbon Addition of the dialkyl or diaryl phosphite generally takes place with the formation of a 1:1 ketone-phosphite adduct, e. g., phorone generally reacts as follows:

Under some conditions, howevenphorpne,as well as other of the present dialkenyl ketones may react with the formation of 1:2 ketone-phosphite adducts, addition of thephosphite taking place at each of the double bonds. The formation of either the 1:1 or the 1:2 adducts depends upon the nature of the individual ketone and phosphite used, as well as upon the reaction conditions employed.

Phosphites useful for the present purpose are dialkyl, dicycloalkyl, diaryl, dialkaryl ordiaralkyl phosphites generally, and preferably those in which each alkyl, aryl, cycloalkyl, aralkyl oralkaryl radical has from 1 to 12 carbon atoms, -e. -g., dimethyl, diethyl, diisopropyl, din-butyl, di-ter-t.-amy1, dicyclohexyl, di-n-hexyl, bis (2-ethylhexyl), di-dodecyl, diphenyl, dibenzyl, di-cresyl, di-p-naphthyl or dixenyl phosphite. i

The addition reaction with mesityl oxide or with phorone, both readily available il-unsaturated ketones, proceeds especially easily, addition of di-esters of phosphorous acid to these ketones generally resulting in the formation of the corresponding addition products in good yields, say, in yields of at least 50%, based on the ketonic constituent. V

Free-radical liberating agents which may be employed in promoting addition of the above phosphites to the olefinic ketones are-compounds which will decompose to give free. radicals. Such compounds include peroxygen-type catalysts, for example 'acyl peroxides such as acetyl, benzoyl, lauroyl or st'earjoyl peroxides; hydrocarbon peroxides or hydroperoxides suchias ditert.-butyl peroxide, di-tert.-amyl peroxide, tert.- butyl hydroperoxide, cumene hydroperoxide or pcymene hydroperoxide; and inorganic per-com- I pounds such as hydrogen peroxide, sodium peroxide, sodium perborate, potassium persulfate, and alkali percarbonates; hydrazine derivatives such as hydrazine hydrochloride :and-dibenzoyl hydrazine; organometallic' compounds *such as tetraethyl lead, etc. .Fbncomienience, the...peroxygen type catalysts will berhereinafterreferred to as peroxidic compounds. Only catalytic quantities of a, free-radical liberating agent need be employed in promoting the addition reaction. Quantities of as little as 0.001 per cent to 1.0 per cent, based on the weight of the ketone, are generally suflicient to give optimum yields of the oxo-phosphon'at'es. In. order to avoid detrimental side reactions, quantities of more. than '5 per cent .of the catalyst, basedjon the weight of the ketonic component should not be employed. Ultra-violet light maybe employed with "the catalyst or as the sole catalytic agent. The addition reaction may be effected simply by contacting the phosphite with the olefinic ketone-in the presence of a free-radical liberating agent such as a peroxidic compound at ordinary or increased temperature, depending upon the nature of the individual reactants employed.

Optimum yields are generally obtained by maintainingthe mixture of reactants and catalyst at a temperature which allows steady decomposition of the catalyst.

For the formation of the mono-phosphonates, one mole of the phosphite may be employed with one mole of the olefinic ketone. Advantageously however, in order to avoid the formation of telomeric products, the phosphite is used in excess. Optimum yields of the oxo-phosphonates are obtained when employing from 3 moles to 5 moles, and even up to 10 moles, of the phosphite per mole of the olefinic ketone.

When working with the dialkenyl ketones, mono-phosphonates are generally formed; however the formation of diphosphonates, i. e., 1:2 ketone-phosphite adducts, by addition of the phosphite at each olefinic bond of the ketone component may occur, depending upon the reaction conditions employed and the nature of the individual reactants.

The present oxo-phosphonates are stable, rather high-boiling materials which range from viscous liquids to Waxy or crystalline solids. They are generally useful for a variety of industrial purposes, for example, as plasticizers for synthetic resins and plastics, as textile lubricants, intermediates for the production of surface-active agents, pharmaceuticals, lubricating oil adjuvants, etc. Particularly valuable as gear lubricant additives are oxo-phosphonates which have the general formula zoi aoz in which'T is selected from the class consisting of the methyl radical and the isobutenyl radical and Z is an alkyl radical of at least 2, but not more than 8 carbon atoms. Such oxo-phosphonates are readily available by the addition reaction "of mesityl oxide or phorone with a dialkyl phosphite in which the alkyl radical has from 2 to 8 carbon atoms. h

When these oxo-phosphonates are blended with suitable base oils, there are obtained ;efil cient gear lubricants for all types of autor-nm tive differentials and conventional transmissions. The extreme pressure-resisting properties which are imparted to lubricants by these oxo-phosphonates results .in the provision of very eflicient lubricants for heavy "duty industrial gear rtype units. 7 v v This invention is further illustrated, but not limited, by the following examples:

Example 1 25 j 4 1'.024 1,-and anaylzing 11.35% phosphorus (calcd. PJf-or -C113H25(34P, 11.21%). i

methyl 4 oxopentane 2 phosphonate. B;j P.

til-86 c./1 mm., 11 1.4462,

'dgg.

1.0296, and anaylzi'ng 13.16% phosphorus" (calcd.

P for C1oH21O4P, 13.11%). Y

Example t I I A mixture consisting of 276g. (2.0moleslof diethyl phosphite, 98*g. (1.0 mole) of -mesity1 oxide and 2.0 cc. of di-tert.-butyl peroxide was heated at a temperature of about 132 C. After four hours, an additional 1.0-cc. portion of ditert.-butyl peroxide was added and heating was continued for 15.5 hours longer. The resulting reaction product was distilled to yield a fraction B. P. 43 C./1.3 mm. to 145 C./3 mm. Redistillation of this fraction gave'a 54% yield=of substantially pure diethyl 2-methyl -4-oxopentane 2-phosphonate.

. Example 4 This example shows the preparation of a crude diethyl 2 methyl-4-oxop'ent'ane 2 phosphonate which was found to be highly efiicient as an ex treme pressure-imparting additive to lubricants.

A mixture consisting of. 690 g."(5.0 moles) of diethyl phosphite, 245'g."(2.5 moles) of mesityl oxide and 5.0 cc'. of di tert-butyl peroxide was heated for 19 hours. The temperature at the beginning was about 130 C.; this dropped to 116 C. owing to refluxing before the end pf'the heating period. Removal of material B. P. ca.- 30" C./150 mm. to 78 C./0.8 mm. from the resulting reaction mixture gave as residue 542.4 g. of an amber liquid, 111 1.4563, consisting largely of the 1: 1 mesityl oxide -diethyl-phosphite adduct, 1. e., diethyl 2-methyl-4-oxopentane 2 phosphonate.

Evaluation of this crude product as a lubricant additive showed that'addition of the product to both solvent and conventionally refined representative (i. e., Pennsylvania, Mid Continent and Coastal) base oils gave lubricants having very good load-carrying capacities at any temperatures likely to be reachedinservice.

. Example 5 I A mixture consisting of 12.8 g. (0.152 mole) of ethylidene acetone, 62.9 g. (0.456 mole) of diethyl phosphite and 0.5 cc. of di-tert.-butyl peroxide was heated to a temperature of about 132 C. and maintained at that temperature for about 5hours. An' additional 0.5 cc. of the peroxide was added to the reaction mixture and heating at about132 C. was continued'for an additional 16 hours. Distillation of the resulting reaction productgave the 1:1 ethylideneacetone-diethyl phosphite add uct probably diethyl 4-oxopentane-Z-phosphonate, B. P. 80-85 C./0.8 mm., n 1.4507,

1.0334, and analyzing 13.18% phosphorus (calcd. P for CsH19O4P,-13.94%).

It is to be understood that the foregoing detailed description is given merely by way of illustration and that many variations may be madetherein without departing from the spirit'of our invention.

What we claim is:

1. The method of preparing diesters of aliphatic oxophosphonic acids which comprises con-v tacting a diester of phosphorous acid with an a s-unsaturated aliphatic ketone in the presence of a free-radical liberating agent.

2."" Ihje method of prep'aring'compou'nds having th'ejgeneral formula j in which R is selected from the class consisting of hydrogen and alkyl radicals, Y is a. hydrocar: bon residue and X is selected from the class-cone sisting of alkyl and ,alkenylradicals, which comprises contactingin the presence of a free-radical liberating agent an ester having the general formula in which is a hydrocarbon-residue, with a ketone having the general formula 1 ii i? R.o;o.c.x

in which R is selected from the class consisting of hydrogen and alkyl radicals and X is selected from the" class' consisting of alkyl and alkenyl ing the general formula I 3. 1

in which R is selected from the'class consisting of hydrogen and alkyl radicals of from 1 to 8 carbon atoms, X is selected from the class consisting of alkyl and alkenyl radicals or from 1 to 8 carbon atoms, and Yis selected from the class consisting of alkyl,.cycloalkyl, aryl, alkaryl and aralkyl radicals of from 1 to 12' carbo'n atoms, which comprisescontacting, in the presence of a free-radical liberating agent,'an ester having the general formula Yo.- .oY

in which Y is selectedfromi the class consistin of alkyl, cycloalkyl, aryl, alkaryl and aralkyl radicals of from 1 to 12 carbon atoms, and a ketone having the general formula I IltR o in which R is selected from the class consisting of hydrogen and alkyl radicals of from 1 to 8 carbon atoms and X is selected from the class consisting of alkyl and-alkenyl radicals 'offrom lsto8 carbon'atoms- Y I .4. The methodclaimed in claim 3 further characterized inthat the free-radicalliberating agent is a'peroxidi'c compound.

aerama 7. r 5. The method of;pre.paring I M R. 0. CH2- C. 81k

in which Y is selected fromttheclass consisting of alkyl', cycloal-kyi, aryl, alkaryl and aralkyl radicals of from 1 to 12 carbon atoms. and'alk denotes an alkyl radical of from 1 to 8. carbon atoma which comprises contacting, in the presence of a freeradical liberating agent, an ester having the general formula V- H YOJEHOY in'wh-ich Y is selectecl'from the class consisting of 'alkyl, cycloalkyl, aryl, alkaryl' "and aralkyl radicalsof from 1 to 12 carbon atoms, withja ke'tonehaving the general formula I i RHO" in which R is selected from the class consisting of hydrogen and alkyl radicals of from 1 to 8 carbon atoms and all: denotes an alkyl radical of from lto Bcarbcn atoms. t

6. The method ofpreparing compounds having. the general formula R 0 I II Yer-or ini whichl a? mi elected 'frommeans; consistin of alkyl; 'cycloalkyl, aryl, alkaryl andg, aralkyl radicals of' from 1 .to 12 carbon atoms, with a ketonehaving the general formula V v 1' V I I ll R.C: .C.alkenyl in which R is selected from the class consisting of hydrogen and alkyl radicals of from 1 to 8 carbon atoms and alkenyl denotes an alkenyl radical of from 2 to 8-c'arbon-a-toms:

- '1; The method of preparing:ketophosphonates having the general'form ila l H CHr-C -CHr-C- p in which Z is an alkyl radicalgofzfrom 1.-.to:r8. carbon atoms;-X is'selectedfrom the @fiSSlQOHSiStr, ing of hydrogen and the methyJzglfBzdical-andiBis selected from the class. consistin'g;-of-;the methyl and the isobutenyl radical, which. comprises OOH? tacting, in the presence of. a-free-radical'liberateing agent, a dialkyl phosphate in which each alkyl radical has from 1. to 8. carbon atoms with aiketone selected from, the class consisting of mesityl oxide... phorone. and ethylidenacetone, and recovering said ketophosphonate from the. re sulting reaction product.

8... The. method of preparing dialkyl 2l-methyl- 4I-oxopentane-2-phosphonates in which each alkyl radical has from 1 to 12 carbon atoms which comprises contacting mesityl Oxide, in the presence of a free-radicalliberating agent, with a. dialkyl phosphite in which each alkyl radical has from 1 to 12 carbon atoms.

- 9.. The method of preparing dialkyl; 2,55 dimethyl 4 oxo 5 hepten 2 phosphonates in which each alkyl radical has from 1 to 12 carbon atoms which comprises contacting phorone; in the presenceof afree-radical liberating agent, with a dialkyl phosphite in which each, alkyl radiealhas from1to12 carbon atoms;

10. The method of preparing dialkyl 4-; oxopentane- 2 phosphonate which comprises contacting ethylidenacetone, in the presenceof a. free-radical liberating agent, with a dialkyl Phosphite which each alkyl radical has from 1 to 12 carbon atoms. v I 1 11. The method of preparing diethyl 2-methyl- 4 oxopentane-Zmhosphonate which 1 comprises contacting mesityl oxide with diethyl phosphi-te in the presence of afree-radical liberating agent.

12. The method of preparing diethyl 2,6- dimethyl 4 0x0 5 hepten 2. phosphonate which comprises contacting phorone with diethyl,

phosphite the presence of a free-radical liberating agent. t 13 he method; of preparing diethyl 4- ozgopentane 2: phosphonate which comprises contacting.ethylideneacetone with diethyl phos phite in the presence of a free-radicalliberating, agent, a I

14.: Ketophosphonates having the formula a Xx," O

011515 0112. d-T f in which Z is an. alkyl radical of fromljto' 8 carbon atoms. X is'sel'ected fromthe cl'a'ssiconsisting of hydrogen and. the methyl radicaland. T1 is. selected from the class, consisting/of. the methyl and the isobutenyl'radical.

.15. Diethyl 2,6 -'.di-methyl. 4 m: 5. o-

Q oxopentane 2 REFERENCES CITED The following] references are ofirecord, intli e 593 3 as .1 v UNITED-swarm PATENTS: Number" it m F Date 7 9 .3 Han-ford et a1. Aug. 9, 1-949 ;99 Harman et-a1. J an. 3-, 1 950 OTHER REFERENCES Arbusov et al., J. Gen. Chem. (U.S.S.R.) vol. 4, pp. 834-41 (1934) as abstracted in Chem. Abstracts, vol. 29, columns 21l5 -.-2146 (1935),, (llgDggke et al., J. Org. Chem vol. 2,'pp'. 387 -396 eneral 

1. THE METHOD OF PREPARING DIESTERS OF ALIPHATIC OXOPHOSPHONIC ACIDS WHICH COMPRISES CONTACTING A DIESTER OF PHOSPHOROUS ACID WITH AN A,B-UNSATURATED ALIPHATIC KETONE IN THE PRESENCE OF A FREE-RADICAL LIBERATING AGENT. 